Petrological Binocular Microscope in Box, by Swift and Son, London, c.1890

The blackened brass tripod carries the curved limb on trunions. The binocular body moves on rackwork for focusing. The eyepieces drop into tubes that can be raced up from the body to adjust the inter-ocular distance. Objectives screw into the lower end of the body. The circular stage rotates. Specimens are held in a mechanical bracket that is moved back and forth and side to side by two mill-headed screws. A rotating disc with three apertures is attached to the underside of the stage. The plano-concave mirror is set in a horseshoe mount on the cylindrical lower end of the limb. The instrument is stored in a wooden carrying case. There are two eyepieces, three objectives in cans, a micrometer eyepiece, a bull's-eye lens on a stand with a weighted base, a brass can and red leather covered case with four glass discs and a glass tube.